1. Field of the Invention
This application relates to locking mechanisms for doors, particularly doors used to separate an aircraft cockpit compartment from an aircraft passenger compartment.
2. Description of the Related Art
In a commercial airliner, a door is typically provided between the cockpit and the passenger area. This is desirable for a number of reasons. The door can be locked with a lock typically being controlled by the crew in the cockpit, such as an electrically operated lock. The door gives the crew in the cockpit a measure of security from disturbances in the passenger area. Also, it isolates the crew from the noise in the passenger area, which is desirable to prevent fatigue and to facilitate concentration. Also, with the cockpit sealed, the air conditioning in the cockpit can be handled in a manner different from the passenger area. This is advantageous for crew performance.
At the same time, it is necessary that the pressure differential between the cockpit and the passenger area not exceed a certain level in that a decompression condition in either area can cause serious structural damage to the airplane. Currently, this goal is accomplished by having a door locking mechanism give way when the door is subjected to a certain force, such as about 160 pounds. Unfortunately, a hijacker can fairly readily manually produce sufficient force to open the door in that fashion. Consequently, a need exists for a system that will provide the necessary privacy, prevent decompression damage, and at the same time provide the necessary security to prevent a hijacker from entering the cockpit. It is, of course, necessary that the system be practical and reliable.